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Chapter 14
Watch Timer (WT)
Preliminary User’s Manual U17566EE1V2UM00
14.2 Watch Timer Registers
The Watch Timer counters WT0 and WT1 are controlled and operated by
means of the following registers:
(1)
WTnCTL - WTn timer control register
The 8-bit WTnCTL register controls the operation of the timer WTn.
Access
This register can be read/written in 8-bit or 1-bit units.
Address
<base> + 6
H
Initial Value
00
H
. This register is cleared by any reset.
Note
1.
When WTnCTL.WTCE is 1, the counter starts after the counter's load
value has been written to the reload register WTnR. As long as WTnR is
zero, no counting is performed, and no interrupts INTWTnUV are
generated.
2.
The first interval from counter start to the first underflow takes at least four
clock cycles more than the following intervals. For details refer to
“Watch
Timer start-up“ on page 486
.
Table 14-2
WTn registers overview
Register name
Shortcut
Address
Watch timer synchronized read register
WTnCNT0
<base>
Watch timer non-synchronized read register
WTnCNT1
<base> + 2
H
Watch timer reload register
WTnR
<base> + 4
H
Watch timer control register
WTnCTL
<base> + 6
H
Table 14-3
WTn register base addresses
Timer
Base address
WT0
FFFF F560
H
WT1
FFFF F570
H
7
6
5
4
3
2
1
0
WTCE
0
0
0
0
0
0
0
R/W
R
R
R
R
R
R
R
Table 14-4
WTnCTL register contents
Bit position
Bit name
Function
7
WTCE
Watch timer counter enable:
0: Disable count operation (the timer stops immediately with the count value
0000
H
and does not operate).
1: Enable count operation.
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